PRB-JURASSIC TETRAPODS. 169 



Family Pholidogasterid^, nov. 



Embolomei'i showing a passage to Rachitomi ? With clavicles 

 expanded on the ventral sui'face. Ventral armour of scutes. 

 (Secondarily aquatic ?) 



J'holidogaster Huxley. Lower Carboniferous, Scotland, 



Family Cricotid^e Cope. 



Embolomeri with elongated skulls. Clavicles expanded on the 

 ventral siuface. Venti'al armoui' of small scutes. (Secondarily 

 aquatic ? ) 



Cricotits Cope. Artinskian, Texas, and ? U. Coal Measures, 

 Illinois. 



Embolomeri incerta sedis. 



Dijilovertebron Fritsch. L. Permian, Bohemia. 

 Nuinmulosaurus ,, ,, ,, 



Macromeriuin ,, ,, ,, 



Spondi/lerj)eton Moodie. U, Carboniferous. Illinois. 



Grade RACHITOMI Cope. 



Labyrinthodonts with ossified basioccipital and basisphenoid. 

 Occipital condyle triple or double. Pterygoids usually with a 

 medium-sized palatal part, interpterygoid vacuities of medium 

 to lai'ge size. Pterygoids aiticulating with both parasphenoid 

 and basisphenoid. Tabulars and dermo-supraoccipitals with 

 occipital flanges. Paroccipital always visible fi-om behind. 



Vertebra? rachitomous, i. e., with small paired pleurocentra 

 and half-moon shaped intercentra. 



Grade STEEEOSPONDYLI Cope. 



Labyrinthodonts with reduced basioccipital and basisphenoid. 

 Occipital condyle double. Pteiygoids with a reduced palatal 

 I'amus, interpterygoid vacuities large to very large. Pterygoids 

 supported by the parasphenoid. Exoccipital meeting the occi- 

 p)ital flange of the tabular so as to hide the paroccipital in an 

 occipital view. 



Vertebrae stereospondylous, i. e., with very i-educed or absent 

 pleurocentra and enlai'ged intercentra. 



I have discussed the classification of the grades Rachitomi and 

 Stei'eospondyli in very great detail in a paper which will, I hope, 

 soon be published ; it is therefoi'e unnecessary to reproduce the 

 division into families on the present occasion. 



Super- Order PHYLLOSPONDYLIA Credner. 



Small, very highly specialised Batrachia with a roofed skull, 

 palate with very widely open interpterygoid vacuities, palatines 

 and lower jaw very reduced. Coracoicl and pubis not ossified. 

 Four-fingered hand. Ventral armour of small round scutes. 



Proc. Zool. Soc— 1917, No. XII. 12 



